Interference between transverse cross-correlated relaxation and longitudinal relaxation affects apparent J-coupling and transverse cross-correlated relaxation

The apparent value of the measured J-coupling is affected by transverse cross-correlated relaxation between dipolar interaction and chemical shift anisotropy. This effect counteracts the decrease in the apparent value of J resulting from self-decoupling caused by longitudinal relaxation, thereby bringing the measured J-coupling closer to its true value. In addition to the dynamic frequency shift and self-decoupling, interference between transverse cross-correlated and longitudinal relaxation processes may serve as a complementary explanation for the deviation between the measured and true J-couplings for small size scalar couplings. The apparent cross-correlated relaxation rate between coupled spins may also be affected by this interference.